The invention discloses a quinonoid compound modified nylon membrane biological carrier and a preparation method and application thereof and belongs to the field of environmental engineering, chemical engineering and materials engineering. By adoption of the technical scheme, a quinonoid compound is fixed to a nylon membrane with excellent pore structure properties and amino active groups through a chemical grafting method, and a quinonoid compound modified nylon membrane biological carrier which is large in quinonoid grafting amount, high in water scouring resistance, stable in mechanical performance, free in biological toxic properties and high in catalytic efficiency is prepared and is applied to biodegradation and bio-denitrification of azo dyes. The quinonoid compound modified nylon membrane biological carrier has the beneficial effects that the preparation method is simple, and the reaction time and cost are saved; the carrier bonding is stable, and the catalytic efficiency is high. In addition, for a microbial denitrification process, the nylon membrane has high toughness and high biocompatibility, is easy to hang, has the characteristic of forming a stable microbial community and is suitable for industrial production and popularization and application.